Oil and gas wells are generally fitted with well bore casing, liner, and fluid production tubing strings for flowing petroleum oil, and gas from an earth formation through the well bore to the surface. In such wells, the tubing string or strings define flow paths through which well fluids may flow while the annulus between the tubing string or strings and the well casing defines an additional flow path which may serve to conduct well fluids to the surface or may contain static liquids for maintaining a hydrostatic head in the well for well known flow control purposes. The tubing strings used in such wells are made up of the necessary number of tubing joints connected together end-to-end to provide communication downwardly in the well from the surface to the desired producing zone.
It is well known practice to include in tubing strings a sliding sleeve type valve having side ports for communicating the bore of the tubing string with the annulus between the tubing string and the well casing. Such sliding sleeve flow control devices may be used to direct flow from the tubing to the casing, or from the casing to the tubing by plugging the tubing below the ports. If desired, flow may occur both within the tubing from below the ports and from the casing annulus into the tubing simultaneously. Circulation and production flow control devices are available with permanently installed internal sleeve valves and with removable sleeve valves. Also, available are solid sleeves sometimes referred to as isolation or pack-off sleeves. The sleeve valve members normally have external annular spaced seals installed in recesses around the sleeves for sealing between the nipple bore surfaces and the sleeve on opposite sides of side ports through the nipple into the annulus. A particular problem with such seals has been encountered when removing a sleeve valve under substantial pressure differentials between annulus and the tubing bore. The seals have been often severely damaged and may be blown out of the recesses around the sleeve when the sleeve moves in the nipple to a bore portion sufficiently enlarged to allow extrusion of the seal.
It is a principal object of the invention to provide a new and improved well flow control device.
It is another object of the invention to provide a well flow control device includable in a well tubing string of a well.
It is another object of the invention to provide a well flow control device of the sliding sleeve type.
It is another object of the invention to provide a sliding sleeve type valve having a retrievable internal sleeve releasably lockable in the nipple of the valve.
It is an especially important object of the invention to provide a retrievable sleeve for a sliding sleeve valve which includes means for equalizing the pressure between the tubing string bore and the well annulus.
It is a still further object of the invention to provide a retrievable pack-off sleeve for a sliding sleeve valve which includes a slot and lug arrangement for locking the retrievable sleeve at a flow equalizing position preliminary to removal of the sleeve from the nipple.
In accordance with the invention there is provided a sliding sleeve valve for a well production tubing string including a tubular landing nipple connectable at opposite ends with tubing joints making up the tubing string, the landing nipple having side flow ports, equalizing ports spaced from the flow ports, a locking and guide lug projecting into the bore of the nipple, and an internal annular latching recess. A retrievable isolation sleeve adapted to fit in the landing nipple and block flow through the side ports of the nipple includes spaced external annular seals located at opposite sides of the nipple side ports when the sleeve is installed in the nipple, equalizing ports in the sleeve positioned for alignment with the equalizing port in the nipple prior to movement of the sleeve seals into larger bore portions of the nipple when removing the sleeve, external J-slots formed in the outer surface of the sleeve for coaction with the nipple lug to guide the sleeve to equalizing, locking, and release positions in the nipple, and latching collet fingers formed in the sleeve for releasably locking with the locking recess in the nipple to latch the sleeve in operating position in the nipple.
Additional objects and advantages of the present invention will be better understood from the following detailed description of a preferred embodiment thereof in conjunction with the accompanying drawings.